JP4114372B2 - Electric motor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a concentrated winding motor that enables high efficiency, low vibration, and low noise, and high efficiency, low noise, low vibration equipment that includes the motor, such as a hermetic compressor and refrigeration equipment. (Refrigerator, freezer, ice maker, showcase, vending machine), air conditioner (air conditioner, dehumidifier), electronic circuit cooling system, car actuator, and a car equipped with the same .
[0002]
[Prior art]
Conventionally, a concentrated winding motor generally used for an air conditioner, a compressor of a refrigerator, or the like includes a stator 40 and a rotor 50 as shown in FIG.
[0003]
The stator core 41 includes a tooth 42 and a substantially annular yoke 45 that connects the outer peripheral side of the tooth 42.
[0004]
At the tip of the teeth 42, there is a teeth tip wide portion 44 protruding in the circumferential direction along the inner diameter portion of the stator core 41. A refrigerant passage 46 is provided on the outer periphery of the stator core 41. This has a through hole between the compressor frame of the hermetic compressor and the stator core 41 when the stator 40 is press-fitted into a compressor frame (not shown) of the hermetic compressor. That is, it becomes a passage for the refrigerant.
[0005]
The teeth 42 are directly provided with three-phase windings 43U, 43V, 43W via an insulator (insulating film, insulator, etc .: not shown). The windings are three phases of U, V, and W phases and are star-connected to each other, and are 120 ° rectangular wave energization driven by energizing two phases of the three phases at the same time. The applied voltage is changed by PWM control.
[0006]
The rotor 50 is rotatably held concentrically with the stator 40 inside the stator 40, and the rotor core 51 in FIG. 12 is an embedded magnet type in which a permanent magnet 52 is embedded. The rotor is shown.
[0007]
End plates (not shown) are attached to both ends of the rotor core 51, and are fixed by passing rivets (not shown) through caulking holes provided in the rotor core 51 and caulking. A shaft is inserted into the shaft hole 53.
[0008]
The rotor 50 rotates around the shaft by a rotating magnetic field generated by a current flowing through the windings 43U, 43V, and 43W applied to the stator 40 and by a rotational force that combines the magnet torque and the reluctance torque.
[0009]
[Problems to be solved by the invention]
In the conventional concentrated winding motor, magnetic flux concentrates on the teeth due to its structure, so that the cogging torque when no current is applied tends to increase.
[0010]
In particular, in an electric motor driven by a rectangular wave voltage or a rectangular wave current, the magnetic pole position generated by energizing the stator winding does not have an electrical angle of 180 °, so that torque pulsation is likely to occur.
[0011]
By the way, when the rotation frequency is f, in a P-pole N-slot motor, n × f × (the least common multiple of P and N) [Hz] (where n is a natural number) depending on the cogging torque. Torque pulsation due to switching causes vibration represented by n × f × (6 × P / 2) [Hz].
[0012]
On the other hand, in a normally used concentrated winding motor, since the ratio of the number of poles P and N is 2: 3, the frequency of vibration due to the cogging torque and the vibration due to torque pulsation coincide.
[0013]
In such a case, there is a problem that noise is increased due to the vibration caused by the above-described cogging torque and torque pulsation.
[0014]
Usually, as a countermeasure against vibration and noise due to cogging torque, a method of increasing the order of vibration and noise generated by cogging torque by providing one or more notches in the wide tip of the tooth is used. In this case, the radial length of the notch is usually shorter than the radial thickness of the wide teeth portion so as not to impair the deterioration of the motor characteristics such as efficiency.
[0015]
On the other hand, particularly in a concentrated winding motor in which the ratio of the number of poles P to the number of slots N is 2: 3, the torque at the time of energization is greater than the cogging torque against vibration and noise of the 12nth order (n is a natural number) of the rotational frequency. Since the influence of pulsation is much greater, if the radial length is smaller than the radial thickness of the wide tip of the tooth, such as the notch that was used in conventional measures against cogging torque, The magnetic flux distribution that appears prominently in the concentrated winding does not change, such as the short-circuited magnetic flux in one tooth tip wide part returns to the rotor, or the magnetic flux inside the tooth does not flow parallel to the radial direction. Torque pulsation could not be reduced sufficiently.
[0016]
Therefore, it is difficult to sufficiently take measures against vibration and noise of the electric motor. This is more noticeable when a permanent magnet is embedded in the rotor.
[0017]
The present invention does not complicate the structure of the stator and the rotor, and further does not impair the characteristics, while sufficiently reducing vibration and noise due to torque pulsation, and a highly efficient and low-powered motor equipped with the motor. The object is to provide equipment with low vibration and low noise.
[0018]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the electric motor of the present invention has, on the inner diameter side of the teeth, the radial width of the wide tip portion of the teeth is Wt, and the length from the end portion on the inner diameter side of the teeth to the root of the tooth intersecting with the yoke is Lt. When the radial length Ls is Ls> Wt and (0.1 × Lt) <Ls <(0.7 × Lt) and the number of poles of the motor is P, the inner diameter of the notch An opening notch is provided in which the rotation width of the side opening is in the range of the opening angle (mechanical angle), (5 / P) <θ <(16 / P) [°] with respect to the rotor center. .
[0019]
Further, when a notch is provided so as to have a bridge portion between the inner diameter side end portion and the inner diameter side end portion of the notch, and the radial width of the bridge portion is Lb, (0.1 × Lt) <(Ls + Lb) <(0.7 × Lt) and Lb <Wt, and when the number of poles of the motor is P, the width in the rotational direction of the inner diameter side end of the notch opens with respect to the rotor center. The angle (mechanical angle) may be in the range of (5 / P) <θ <(16 / P) [°].
[0020]
With such a motor configuration, it is possible to reduce vibration and noise due to cogging torque and torque pulsation.
[0021]
In addition, because the structure is simply provided with a notch in the teeth, the structure of the stator and rotor does not become complicated, causing problems such as worsening productivity and requiring extra production equipment. Absent.
[0022]
Furthermore, by optimizing the dimensions of the notch so that vibration and noise can be reduced without affecting the characteristics such as efficiency, only vibration and noise due to cogging torque and torque pulsation can be obtained without reducing the efficiency of the motor. Can be reduced.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
The invention described in 請 Motomeko 1, the outer peripheral portion of the the teeth wide distal part provided with a plurality of teeth arranged at substantially equal intervals and substantially radially on the inner diameter side of the teeth with respect to the rotational direction of the teeth A stator having a concentrated winding on the teeth of the stator core having an annular yoke arranged and having slots (winding grooves) between adjacent teeth; and the stator In the electric motor constituted by a rotor that is arranged in a rotor iron core that is opposed to the inner periphery of the rotor with a small gap and is rotatably held, the teeth are opened on the inner diameter side of the teeth. A notch is provided, and when the radial width of the wide tip end portion of the tooth is Wt and the length from the inner end portion of the teeth to the root portion of the tooth intersecting with the yoke is Lt, the radial direction of the notch Length Ls is Ls Wt and (0.1 × Lt) <Ls <(0.7 × Lt), and when the number of poles of the motor is P, the rotational width of the inner diameter side opening of the notch is centered on the rotor On the other hand, it is an electric motor characterized by being in the range of opening angle (mechanical angle), (5 / P) <θ <(16 / P) [°], from the permanent magnet inside the rotor core through the teeth. The leakage magnetic flux to the adjacent permanent magnet can be suppressed, and the electrical characteristics of the motor such as efficiency are not deteriorated by optimizing the notch dimensions.
[0024]
According to a second aspect of the present invention, a plurality of teeth arranged at substantially equal intervals and in a substantially radial direction with respect to the rotation direction, a tooth tip wide portion provided on the inner diameter side of the teeth, and an outer peripheral portion of the teeth are arranged. A stator having a concentrated winding on the teeth of the stator core having slots (winding grooves) between adjacent teeth, and In an electric motor constituted by a rotor having a permanent magnet disposed inside a rotor core that is opposed to the inner periphery with a small gap and is rotatably supported, the teeth are provided with notches, A bridge portion is provided between the inner diameter side end portion of the notch and the inner diameter side end portion of the tooth, the radial length of the notch is Ls, the radial width of the bridge portion is Lb, and the inner diameter side end portion of the tooth Teeth that intersect with the yoke When the length to the base is Lt, (0.1 × Lt) <(Ls + Lb) <(0.7 × Lt) and Lb <Wt, and when the number of poles of the motor is P, The width in the rotational direction of the inner diameter side end of the notch is in the range of opening angle (mechanical angle), (5 / P) <θ <(16 / P) [°] with respect to the rotor center. It is an electric motor, and it is possible to suppress the leakage flux from the permanent magnet inside the rotor core to the adjacent permanent magnet through the teeth, and by optimizing the notch dimensions, The physical characteristics are not degraded.
[0025]
The invention according to claim 3 is characterized in that the notch provided in the tooth is provided inclined by an angle θs from a line connecting the center of the tooth and the center of the rotor with respect to the rotation direction, and θs <20 [°]. The electric motor according to claim 1 or 2, wherein the flow of magnetic flux can be induced in the inclination direction of the notch.
[0026]
The invention according to claim 4 is the electric motor according to any one of claims 1 to 3, characterized in that a nonmagnetic material is embedded in a notch provided in a tooth. Teeth vibration caused by the provision can be suppressed.
[0027]
The invention according to claim 5 is the electric motor according to claim 4, wherein the nonmagnetic material embedded in the notch provided in the tooth has electrical insulation, and the motor characteristics such as efficiency are impaired. The vibration of the teeth can be suppressed.
[0028]
The invention according to claim 6 is a device including the electric motor according to any one of claims 1 to 5, and can achieve low vibration and low noise of the device.
[0029]
【Example】
Hereinafter, specific examples of the present invention will be described with reference to FIGS.
[0030]
(Example 1)
As shown in FIG. 1, the concentrated winding electric motor used for an air conditioner, a compressor of a refrigerator, etc. includes a stator 10 and a rotor 20, and the stator 10 includes six stator cores 11. Three-phase windings 13U, 13V, and 13W are directly applied to the teeth 12 via an insulator (not shown) between the windings and the stator core.
[0031]
The stator core 11 faces the outer periphery of the teeth 12 on which the winding is applied and the rotor 20, and connects the teeth distal end wide portion 14, which is normally disposed at the tip of the teeth 12, between the teeth. It consists of a substantially annular yoke 15. A refrigerant passage 16 is provided on the outer periphery of the stator core 11.
[0032]
The refrigerant passage 16 has a through hole between the compressor frame of the compressor and the stator core 11 when the stator 10 is press-fitted into the compressor frame (not shown) of the compressor. It becomes a passage for the refrigerant.
[0033]
The tooth 12 is provided with a substantially rectangular cutout 17. 1 shows a case where the notch 17 is open to the inside diameter side of the tooth, and FIG. 2 shows a case where a bridge portion 18 is provided between the notch 17 and the end part on the inside diameter side of the tooth.
[0034]
FIG. 3 shows the harmonic content with respect to the basic waveform of torque pulsation when the radial length Ls of the notch 17 is changed. 3 is expressed by α = Ls / Lt (Lt is the length from the inner diameter side of the teeth to the root of the teeth where the teeth 12 and the yoke 15 intersect), the number of poles P = 4, and the slot The characteristic when number = 6 is shown.
[0035]
Further, FIG. 1 shows a case where the notch 17 is opened on the inner diameter side of the tooth, but when the bridge portion 18 is provided as shown in FIG. What is necessary is just to substitute and consider as Ls + Wb (Wb is radial direction thickness of the bridge | bridging part 18).
[0036]
When reducing the noise of the electric motor, in particular, the influence on the vibration and noise of the 12-fold component of the rotation frequency (12th order) becomes a problem. From FIG. 3, by setting 0.1 <α <0.7, It can be seen that the harmonics of the 12th-order component can be reduced by 2% or more compared to the case where there is no notch (that is, α = 0).
[0037]
In order to minimize the vibration and noise of the 12th-order component of the rotational frequency, α = 0.4 is desirable. On the other hand, since the 24th-order component increases, 0.1 <α <0. Within the range of 7, it can be said that the dimensions should be able to achieve both the 12th and 24th order vibration and noise level targets.
[0038]
FIG. 4 shows the harmonic content with respect to the fundamental wave of torque pulsation when the opening angle θ of the inner diameter side end of the notch 17 is changed. Note that the horizontal axis β in FIG. 4 is represented by β = θ × P (P is the number of poles), and shows the characteristics when the number of slots = 6. In this case as well, as in FIG. 3, the influence on the vibration and noise of the 12-fold component (12th order) of the rotation frequency becomes a problem. However, from FIG. 4, by setting 5 <β <16, there is no notch (that is, It can be seen that the harmonics of the 12th-order component can be reduced by 2.5% or more compared to (β = 0). For the 24th and 36th components, the harmonic content decreases as β is decreased.
[0039]
Therefore, β = 11 is desirable for vibration and noise reduction. However, if β value is determined within a range of 5 <β <16 while considering productivity such as core punching of an electric motor, vibration is reduced. Moreover, noise can be reduced, and an electric motor with good productivity can be obtained.
[0040]
FIG. 5 compares the average torque and torque pulsation of the electric motor configured in the range of α and β shown in FIG. 3 and FIG. 4 and the electric motor having no notch.
[0041]
As is apparent from FIG. 4, even when notches are provided, the average torque is hardly changed, and therefore, characteristics such as efficiency are hardly impaired with respect to an electric motor having no notches. Further, torque pulsation does not increase. As described above, according to the electric motor of the present invention, the vibration and noise corresponding to the 12nth order (n is a natural number) of the rotation frequency can be reduced or optimally adjusted with respect to the target value, and the characteristics of the electric motor are hardly impaired. .
[0042]
The shape of the notch 17 may be a substantially triangular shape, or the shape of the outer diameter side or / and the inner diameter side end of the notch 17 may be a substantially arc shape.
[0043]
Further, as shown in FIG. 6, the notch 17 may have an inclination with respect to a line connecting the center of the teeth and the center of the rotor with respect to the rotation direction. In this case, the inclination θs of the notch 17 is desirably θs <20 [°] so as not to impair the characteristics of the electric motor.
[0044]
7 shows the shape of the notch 17 having a substantially triangular shape, and FIG. 8 shows the shape of the outer diameter side end of the notch 17 having a substantially arc shape.
[0045]
On the other hand, in order to suppress not only cogging and torque pulsation but also motor vibration and noise caused by the vibration of the teeth 12, the nonmagnetic metal material 19 is embedded in the notches 17 as shown in FIG. The rigidity of 12 may be increased. As a result, the vibration and noise of the motor can be further reduced, and since it is non-magnetic, the magnetic flux distribution is almost the same as when there is no notch, so that it is possible to minimize deterioration of the characteristics of the motor. Become.
[0046]
It is also effective to embed or fill the notch 17 with a resin material. By using a resin material, the rigidity of the teeth 12 can be increased, and further, vibration and noise can be reduced. In addition, non-magnetic and insulating properties make the magnetic flux distribution equivalent to that without a notch, and almost no electric motor. There is no loss of characteristics. As the resin material, resins such as PPS, PET, PBT, PA, PTFE, and LCP can be used.
[0047]
In particular, these resins are particularly suitable when used in a refrigerant, such as a hermetic compressor. Furthermore, by making the thermal expansion coefficient of the resin larger than that of the iron-based material constituting the stator core 11, it is possible to hold the teeth 12 more firmly by the heat generated during operation of the electric motor, and to further vibrate the teeth 12. It becomes possible to suppress. The effect is particularly great when used at high temperatures.
[0048]
Further, when the driving power source is a battery mounted on an automobile or the like, that is, when the voltage applied between the winding terminals of the motor is 50 V or less, for example, 12, 24 or 42 V, etc., low vibration of the device In addition to low noise, the motor is highly efficient and can be operated for a long time.
[0049]
(Example 2)
FIG. 10 shows a hermetic compressor equipped with the electric motor of the present invention. In FIG. 10, the hermetic compressor 100 includes a frame 101 for sealing the inside of the compressor with respect to the outside, a mechanical unit 102 that performs compression, a stator 10, and a rotor 20. The stator 10 is fixed to the compressor frame 101 by shrink fitting or press fitting, and the rotor 20 is fixed to the shaft 103 extending from the mechanical unit 102 by shrink fitting or press fitting.
[0050]
In consideration of the environment, the type of refrigerant used is preferably HFC or natural refrigerant (CO ₂ , ammonia, etc.).
[0051]
Similarly, when used in a car actuator, it is possible to realize low vibration, low noise, small size, and low cost of the device. Vibration, low noise, small size, and low cost can be realized.
[0052]
Further, FIG. 11 shows a refrigeration cycle having the above-mentioned hermetic compressor, which is composed of a hermetic compressor, a condenser and an evaporator, and is mounted on various devices. It is installed in refrigeration equipment (refrigerator, freezer, ice machine, showcase, vending machine), air conditioner (air conditioner, dehumidifier), electronic circuit cooling system, and the like.
[0053]
【The invention's effect】
As is apparent from the above description, according to the present invention, a notch opened on the inner diameter side of the tooth is provided, and the length Ls in the radial direction of the notch is Ls> Wt and (0.1 × Lt) <Ls. <(0.7 × Lt) (Wt is the radial width of the tooth tip wide portion, Lt is the length from the inner diameter side end portion of the tooth to the tooth root portion intersecting with the yoke), The width in the rotation direction of the inner diameter side opening of the notch is an opening angle (mechanical angle) with respect to the center of the rotor, (5 / P) <θ <(16 / P) [°] (where P is the number of poles) By being in the range, it is possible to reduce or adjust vibrations and noises corresponding to the 12n-th order (n is a natural number) of the rotation frequency without impairing the motor characteristics such as efficiency.
[0054]
Further, according to the present invention, when a notch is provided in the tooth and a bridge portion is provided between the inner diameter side end of the notch and the tooth inner diameter side end, the length of the notch in the radial direction is determined. Ls is (0.1 × Lt) <(Ls + Lb) <(0.7 × Lt) and Lb <Wt (Wt is the radial width of the wide tip of the tooth, and Lt is from the inner diameter side end of the tooth. , The length to the tooth root that intersects the yoke, Lb is the thickness of the bridge portion, and the rotational width of the inner diameter side end of the notch is an opening angle (mechanical angle) with respect to the rotor center. ), (5 / P) <θ <(16 / P) [°] (where P is the number of poles), so that the 12n-th order (n is the rotation frequency) without impairing the motor characteristics such as efficiency. Vibration or noise that is a natural number) can be reduced or adjusted.
[0055]
In addition, the vibration and noise of the electric motor can be further reduced by inclining the notch by an angle θs [°] of less than 20 [°] from a line connecting the center of the teeth and the center of the rotor with respect to the rotation direction.
[0056]
In addition, by embedding a non-magnetic material in the notch, the vibration and noise of the motor caused by the vibration of the teeth itself can be reduced, so that the vibration and noise of the motor can be further suppressed and the characteristics of the motor are reduced. Can be minimized.
[0057]
Furthermore, the characteristic loss of the electric motor can be further reduced by using the non-magnetic material as a material having electrical insulation.
[0058]
In addition, by mounting the electric motor according to the present invention having the above-described specific effects on a hermetic compressor, a refrigeration apparatus, an air conditioner, an electronic circuit cooling system, a car actuator, an automobile equipped with the same, etc., low vibration of these apparatuses Low noise and high efficiency can be realized.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a concentrated winding motor in which a notch according to the present invention is open to the inner diameter side of a tooth. FIG. 2 is a concentrated winding in which a bridge is provided between the notch according to the present invention and an end portion on the inner diameter side of a tooth. Cross section of electric motor [Fig. 3] Characteristic diagram of harmonic content of torque pulsation with respect to variable α that determines the radial length of the notch [Fig. 4] Variable that determines the rotational width at the tooth tip of the notch Characteristic diagram of harmonic content of torque pulsation with respect to β [Fig. 5] Characteristic diagram comparing average torque and torque pulsation with and without notch [Fig. 6] Inclined notch of the present invention FIG. 7 is a cross-sectional view of a tooth portion having a substantially triangular cutout according to the present invention. FIG. 8 is a cross-sectional view of the outer diameter side end portion of the present invention having a substantially arc-shaped cutout. Cross section of teeth [FIG. 9] Non-magnetic in notch of the present invention FIG. 10 is a diagram showing a hermetic compressor equipped with the electric motor of the present invention. FIG. 11 is a diagram showing a refrigeration cycle equipped with the hermetic compressor of the present invention. ] Cross-sectional view of a conventional concentrated winding motor [Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Stator 11 Stator iron core 12 Teeth 14 Teeth tip wide part 15 Yoke 17 Notch 18 Bridge part 20 Rotor

Claims (6)

A plurality of teeth arranged at substantially equal intervals and in a substantially radial direction with respect to the rotation direction; a teeth tip wide portion provided on an inner diameter side of the teeth; and an annular yoke arranged on an outer peripheral portion of the teeth. , the teeth of the stator core slot is provided between adjacent teeth, face each other through a stator formed by subjecting a concentrated winding, a slight gap on the inner periphery of the stator, rotatably In the electric motor constituted by a rotor in which a permanent magnet is arranged inside the rotor core held in the tooth, a notch opened on the inner diameter side of the tooth is provided in the tooth, and the radial width of the wide end portion of the tooth is set. Wt, where Lt is the length from the teeth inner diameter side end portion to the tooth root portion intersecting with the yoke, the length Ls in the radial direction of the notch is Ls> Wt and (0.1 × Lt) <Ls <( Together .7 is × Lt), the number of poles of the motor when is P, the opening angle with respect to the rotational direction width rotor center of the cutout inner diameter side opening, (5 / P) <θ <( 16 / P) An electric motor in the range of [°]. A plurality of teeth arranged at substantially equal intervals and in a substantially radial direction with respect to the rotation direction; a teeth tip wide portion provided on an inner diameter side of the teeth; and an annular yoke arranged on an outer peripheral portion of the teeth. , the teeth of the stator core slot is provided between adjacent teeth, face each other through a stator formed by subjecting a concentrated winding, a slight gap on the inner periphery of the stator, rotatably In the electric motor constituted by a rotor in which a permanent magnet is arranged inside the rotor core held by the rotor, a notch is provided in the teeth, and an inner diameter side end portion and an inner diameter side end portion of the notches are provided. A bridge portion is provided between them, the notch radial length is Ls, the radial width of the bridge portion is Lb, and the length from the teeth inner diameter side end portion to the tooth root portion intersecting with the yoke When Lt is Lt, .1 × Lt) <(Ls + Lb) <(0.7 × Lt) and Lb <Wt (the radial width of the wide tip of the tooth), and when the number of poles of the motor is P, the inner diameter of the notch An electric motor characterized in that the width in the rotational direction of the side end portion is in the range of an opening angle with respect to the rotor center, (5 / P) <θ <(16 / P) [°].   The notch provided in the teeth is provided by being inclined by an angle θs from a line connecting the center of the teeth and the center of the rotor with respect to the rotation direction, and θs <20 [°]. The electric motor described in 1.   The electric motor according to any one of claims 1 to 3, wherein a nonmagnetic material is embedded in a notch provided in the tooth.   The electric motor according to claim 4, wherein the nonmagnetic material embedded in the notch provided in the teeth has electrical insulation.   An apparatus comprising the electric motor according to any one of claims 1 to 5.

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